poly for outdoor plywood signs

We have some painted holiday "mice" as a chorus created by an Uncle - very nice paintings... They are 1/4" plywood - painted.
They are showing signs of "weathering", and would like suggestions on how to keep them in great shape ??
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/ _/ _/ _/ _/ _/ _/ _/ _/ _/ _/ _/ _/ _/ _/ _/ _/ _/ _/ _/
No Good Deed -
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---------- BTW - they are only outside for the holiday season...
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On Tue, 22 Apr 2014 18:05:23 -0500, "ps56k"

Are they painted on all 6 sides?
The edges of plywood are more important than the faces. That is how the water gets in.
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I would go to any marina or store that caters to the boating public and buy some "Spar" or "Marine" varnish for your mice signs.
Spar (aka: Marine) varnish is intended to withstand exposure to the elements as it's original purpose was in coating and sealing the exposed wooden spars on tall ships. It's most important when protecting any wood from the elements to treat the end grain of the wood. This is because wood absorbs moisture through it's end grain 15 times faster than it absorbs moisture across it's grain. So, weathering of wood usually is the result of the absorbtion of rain water or snow melt into the end grain of the wood. Where you have plywood, you have end grain along the entire periphery of the plywood.
Oil based coatings typically will yellow with age when used in a place with dim or minimal lighting. However, in direct or indirect sunlight, the Sun's rays will remove that acquired yellow discolouration. So, while you might a yellowish tint on the paintings from the spar varnish itself, any further yellowing will be eliminated once the paintings are exposed to direct or indirect sunlight for a few weeks. It would be best to arrange the paintings somewhere in your yard that receives a fair bit of sunlight for a few weeks before putting them on display for the general public to see.
Museum curators, who typically have far more paintings (done in oil) than they could ever put on display at one time will have sunny rooms in the museum where they can put oil based paintings that they intend to put on display in a few weeks. That way, the public sees the painting the way the painter painted it, not in it's yellowed condition after spending years in dimly lit storage rooms.
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nestork

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tnx all - Hadn't thought about the "marine" aspect of coating the wood. And yeah, it's probably the edges that are allowing the water infiltration. I'll look around for some options to coat the edges, and the rest of the sides.

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'Mike Marlow[_2_ Wrote: > ;3226486']

> investigate

> equal

> thinking

> but

To be perfectly honest, I expect the difference between one Marine varnish and another are small compared to the similarities. Any place that sells Marine varnish is always going to recommend a product they sell, so how does one tell a good Marine varnish from a lousy one? Recommendations from friends? What happens if your friends know less about it than you do?
--
nestork


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ps56k wrote:

------------------------------------------------
"Mike Marlow" wrote:

----------------------------------------------------- Mike is right, the last thing you want to use is a true spar varnish.
Spar varnish NEVER completely hardens since it is designed to flex with the wooden spar when under load while sailing.
Haven't seen the signs, but if it was me, I would take some 100 grit sandpaper and sand the raw plywood edges then coat with epoxy from somebody like System 3, WEST systems, etc.
This will get you to System3.
http://tinyurl.com/mqutjkg
Allow about a week and then apply marine varnish such as Epifanes available from West Marine or Jamestown Distributers which will provide the UV protection for the epoxy as well as the wood.
This will get you started.
http://tinyurl.com/mzrlg7j
Have fun.
Lew
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On 4/23/14 8:38 PM, Lew Hodgett wrote:

Good stuff that Epifanes! I had a few old cans of Minwax 'spar varnish' that I used on some outdoor wood (only lasted a few months in the Southwest sunshine). Bought a can of the Jamestown dist. 'Epifanes' and after several years things are still peachy.
I used the System III on some wood clappers for giant wind chimes and it bit the dust after about three years. Stuff that I sprayed with clear coat automotive paint is completely unphased (gawd awful expensive nowadays though).
-Bruce

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On 4/26/2014 10:00 AM, Brewster wrote:

Epoxy should be coated with a uv protectant. It will degrade if left in the sun. Generally epoxy followed by spar is a good finish, since spar has uv protection. Also I saw someone in a mag recommended the clear base from an exterior paint. It's clear until colored he said.
--
Jeff

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On 4/26/14 5:26 PM, woodchucker wrote:

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On 4/27/2014 10:22 AM, Brewster wrote:

--
Jeff

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On 4/27/14 8:46 AM, woodchucker wrote:

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I think you folks are over thinking this. I have a salt water pontoon boat with a plywood deck that is used 12 months a year. 25 years ago I replaced the deck and when I sealed the plywood I just used Home Depot house paint to seal the edges of the plywood (along with the faces). I did soak it in as best I could. 2 1/2 decades later, the only place I had any problem was an unsealed penetration that started going on me. I cut out the bad part, sealed it and I was good to go.
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"Mike Marlow" wrote:

----------------------------------------------------- Lew Hodgett wrote:

-------------------------------------------------------- Lew Hodgett wrote: <snip>

----------------------------------------------------------- "woodchucker" wrote: <snip>

<snip> ---------------------------------------------------- What part of the above post didn't you read and understand?
Lew
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On 4/26/2014 8:35 PM, Lew Hodgett wrote:

One could ask you the same.. why didn't you read what I wrote. I was responding to the fact that epoxy alone did not last. Which is a given since it needs a UV protectant.
Spar alone is not perfect either. The two together are very good. The spar contains the UV protectant and the epoxy keeps the piece water proof. Another thing is the spar is sacrificial, meaning it will degrade ... sand it off as it becomes chalky and re-apply. The epoxy should still be good.
--
Jeff

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wrote:

Every untinted paint I have ever seen was white.
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